A substrate processing apparatus for performing a plasma process on a wafer as a substrate includes an evacuable chamber that accommodates the wafer therein; a shower head that introduces a processing gas into the chamber; and a susceptor (mounting table) that is positioned to face the shower head within the chamber and serves to mount the wafer thereon and applies a high frequency power to the inside of the chamber. The processing gas introduced into the chamber is excited into plasma by the high frequency power, and positive ions or radicals in the plasma are used for the plasma process of the wafer.
While the plasma process is being performed, the wafer may receive heat from the plasma, and, thus, a temperature of the wafer increases. If the temperature of the wafer increases, radical distribution on the wafer changes and a chemical reaction rate on the wafer also varies. Accordingly, to achieve a desired result in the plasma process, the temperature of the wafer, more specifically, the temperature of the susceptor mounting the wafer needs to be controlled.
In this regard, in accordance with a recent substrate processing apparatus, a heat transfer heater and a coolant path are provided within a susceptor to control the temperature of the susceptor. The heat transfer heater may heat the susceptor, and a coolant flowing through the coolant path may cool the susceptor. Here, a temperature of the coolant or a flow rate of the coolant may not be accurately controlled, whereas a heat generation amount of the heat transfer heater can be accurately controlled. Thus, in order to accurately control the temperature of the susceptor, the heat transfer heater is operated when necessary while constantly flowing the coolant through the coolant path (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Laid-open Publication No. H7-183276
In the above-mentioned substrate processing apparatus, however, since the coolant constantly flows through the coolant path, a part of heat from the heat transfer heater may be absorbed into the coolant flowing through the coolant path even when it is attempted to increase the temperature of the susceptor by generating heat from the heat transfer heater. Thus, it takes time to increase the temperature of the susceptor and, also, the temperature of the wafer. Furthermore, since not a total amount of heat from the heat transfer heater is used for the temperature rise of the susceptor, there has been a great loss of thermal energy.